Smokers in Canada are facing some of the world's hardest-hitting health warnings on tobacco products.

Canadian cigarette packets will now carry health warnings including colour photographs of diseased internal organs damaged by smoking.

The cigarette makers tried to have the warnings banned. But government officials say the blunt messages are necessary to help improve public health.

Tobacco companies lost a court battle over the warnings

The photos of body parts removed during post mortem examinations include a lung with cancer, a diseased heart and a brain that has suffered a stroke.

Another warning depicts a drooping cigarette accompanied by a message about tobacco-related impotence.

The visual impact of the images will be helped by their size. The rules from the Canadian Health Department say the warnings will have to cover 50% of the packet.

If smokers are not deterred by the image on the outside and open the packet, they will see more detailed written health information on the inside.

Test case

There are also new, less hard-hitting warnings for cigars, and pipe and chewing tobacco.

The health warning regulations have angered the tobacco companies. They complained about them on a number of grounds, saying the new packets would be too technically difficult to print and would not allow enough room for their trademarks.

They also launched an unsuccessful court challenge against the government's proposals.

The impact of the Canadian initiative is being studied by other public health authorities around the world, including those of the European Union, where more hard-hitting tobacco health warnings are being proposed.